The proposed studies are directed at obtaining further information on the regulation and function of the pentose phosphate pathway in neural tissue. More specifically this includes: (1) Extend quantitative histochemical studies of changes in the distribution of enzymes and substrates of this pathway in discrete areas of the cerebellum and spinal cord during early development and myelination. (2) Continue investigations of kinetic properties of enzymes implicated as regulatory steps, particular attention will be directed at determining factors which influence the activity of phosphoribosylpyrophosphate synthetase and ribose-5-phosphate isomerase. (3) Determine the effects of known inhibitors of the pentose phosphate pathway, such as 6-aminonicotinamide, thiamine antagonists and dehydroepinandrosterone, on cellular events in neural tissue.